Nuclear waste dump could be unstable

Mar 27, 1998

Tectonic activity under the proposed nuclear waste dump in the US may have been underestimated. Researchers predict that the Yucca Mountain region in Nevada could suffer 5 to 50 large earthquakes every 10,
000 to 100,
000 years.

The new findings is reported by Brian Wernicke and
colleagues from the
California Institute of Technology (Caltech) and
the
Harvard-Smithsonian Center for Astrophysics in the
current issue of Science
.
Since 1991 Wernicke and
colleagues have been using the
satellite-based Global Positioning System to measure the
movement of Yucca Mountain with unprecedented precision.
The team also used measurements made on a 14 km track across the
proposed dump site by the
US Geological Survey between 1983 and
1997.
The researchers found that the
south east region of the
mountain had "moved significantly" to the
south east at a rate of between 1 and
1.7 mm per year.

At first the researchers thought that an earthquake on the nearby Little Skull Mountain in 1992 could have caused the movement,
but further calculations led them to conclude that Yucca Mountain itself suffers sharp periods of accumulated strain - in other words the region is in an period of increased earthquake and volcanic activity.

Although nuclear waste dumps are not currently designed to withstand earthquakes,
Wernicke believes that increased tectonic activity should not prevent the storage of nuclear waste at Yucca Mountain providing that the activity is taken into account in the design.